Display device and electronic apparatus

ABSTRACT

According to an aspect, a display device includes: a display section that has a first period to consume predetermined power and a second period to consume less power than in the first period, and power consumption of which periodically changes by repeating the first period and the second period; a smoothing capacitor that stabilizes power supplied to the display section; and a power consumption unit that consumes the supplied power in the second period.

CROSS REFERENCES TO RELATED APPLICATIONS

The present application is a continuation of U.S. patent applicationSer. No. 14/204,519, filed on Mar. 11, 2014, which application claimspriority to Japanese Priority Patent Application JP 2013-065177 filed inthe Japan Patent Office on Mar. 26, 2013, and Japanese Priority PatentApplication JP 2013-232339 filed in the Japan Patent Office on Nov. 8,2013, the entire content of which is hereby incorporated by reference.

BACKGROUND

1. Technical Field

The present disclosure relates to a display device that displays animage and an electronic apparatus including the display device.

2. Description of the Related Art

In recent years, various types of display devices such as liquid-crystaldisplay devices, plasma display devices, and organic-electroluminescence(EL) display devices are developed in view of display quality, powerconsumption, and the like, and are applied to various electronicapparatuses such as mobile phones and personal digital assistants aswell as stationary display devices according to the characteristicsthereof.

The display device generally displays an image by performingline-sequential scanning (for example, Japanese Patent ApplicationLaid-open Publication No. 2010-250030 and Japanese Patent ApplicationLaid-open Publication No. 2011-76708). Specifically, for example, in theliquid-crystal display device, a scan-line-signal drive circuit (a gatedriver) first selects one row (one horizontal line) from among pixelsarrayed in a matrix as a target for display drive. Then, a signal-linedrive circuit (a source driver) supplies a pixel signal to the selectedpixels. This configuration causes the pixel signal to be written in thepixels associated with the selected one horizontal line. The displaydevice performs such a write operation of a pixel signal whilesequentially scanning the entire display surface, thereby displaying animage.

A smoothing capacitor is sometimes incorporated into a power supply ofthe display device. The smoothing capacitor suppresses variations of apower supply voltage. This configuration stabilizes power supplied tothe display device. However, in some operation conditions of the displaydevice, a voltage applied to the smoothing capacitor may periodicallychange. If the voltage applied to the smoothing capacitor periodicallychanges, the smoothing capacitor may vibrate due to a piezoelectriceffect and the audible noise may occur.

For the foregoing reasons, there is a need for a display device and anelectronic apparatus that can suppress or reduce the audible noise of asmoothing capacitor.

SUMMARY

According to an aspect, a display device includes: a display sectionthat has a first period to consume predetermined power and a secondperiod to consume less power than in the first period, and powerconsumption of which periodically changes by repeating the first periodand the second period; a smoothing capacitor that stabilizes powersupplied to the display section; and a power consumption unit thatconsumes the supplied power in the second period.

According to another aspect, an electronic apparatus includes thedisplay device.

Additional features and advantages are described herein, and will beapparent from the following Detailed Description and the figures.

BRIEF DESCRIPTION OF THE FIGURES

FIG. 1 is a block diagram of a configuration example of a display devicewith a touch detection function;

FIG. 2 is an explanatory diagram illustrating a state where a finger isneither in contact with nor in proximity to a touch detection device forexplaining a basic principle of capacitive touch detection;

FIG. 3 is an explanatory diagram of an example of an equivalent circuitof a state where a finger is neither in contact with nor in proximity tothe touch detection device illustrated in FIG. 2;

FIG. 4 is an explanatory diagram illustrating a state where a finger isin contact with or in proximity to the touch detection device forexplaining the basic principle of capacitive touch detection;

FIG. 5 is an explanatory diagram of an example of an equivalent circuitof the state where a finger is in contact with or in proximity to thetouch detection device illustrated in FIG. 4;

FIG. 6 is an example of waveforms of a drive signal and a touchdetection signal;

FIG. 7 is an example of a module on which the display unit with a touchdetection function is mounted;

FIG. 8 is a perspective view of a configuration example of driveelectrodes and touch detection electrodes of a display unit with a touchdetection function;

FIG. 9 is an example of coupling of a power supply circuit toconstituent elements of the display device with a touch detectionfunction;

FIG. 10 is a configuration example of a power consumption unit accordingto a first embodiment;

FIG. 11 is a waveform chart representing a first operation example ofthe first embodiment;

FIG. 12 is a waveform chart representing a second operation example ofthe first embodiment;

FIG. 13 is a waveform chart representing a third operation example ofthe first embodiment;

FIG. 14 is a configuration example of a power consumption unit accordingto a second embodiment;

FIG. 15 is a comparative example to the second embodiment;

FIG. 16 is a waveform chart representing an example of an operation ofthe second embodiment;

FIG. 17 is a waveform chart representing an example of the operation ofthe second embodiment;

FIG. 18 is a diagram illustrating a first modification of the secondembodiment;

FIG. 19 is a diagram illustrating a second modification of the secondembodiment;

FIG. 20 is a diagram illustrating a third modification of the secondembodiment;

FIG. 21 is a configuration example in a case where an operation of adisplay section is checked;

FIG. 22 is a configuration example of a power consumption unit accordingto a third embodiment;

FIG. 23 is a waveform chart representing an example of an operation ofthe third embodiment;

FIG. 24 is a waveform chart representing an example of the operation ofthe third embodiment;

FIG. 25 is a configuration example of a power consumption unit accordingto a fourth embodiment;

FIG. 26 is a waveform chart representing an example of an operation ofthe fourth embodiment;

FIG. 27 is a configuration example of a power consumption unit accordingto a fifth embodiment;

FIG. 28 is a waveform chart representing an example of an operation ofthe fifth embodiment;

FIG. 29 is a waveform chart representing an example of changes in powersupply voltages and a voltage value of a drive signal in a touchdetection period and a display operation period;

FIG. 30 is an example of an electronic apparatus to which the displaydevice with a touch detection function according to one of theembodiments and the modifications thereof is applied;

FIG. 31 is another example of the electronic apparatus to which thedisplay device with a touch detection function according to one of theembodiments and the modifications thereof is applied;

FIG. 32 is still another example of the electronic apparatus to whichthe display device with a touch detection function according to one ofthe embodiments and the modifications thereof is applied;

FIG. 33 is still another example of the electronic apparatus to whichthe display device with a touch detection function according to one ofthe embodiments and the modifications thereof is applied;

FIG. 34 is still another example of the electronic apparatus to whichthe display device with a touch detection function according to one ofthe embodiments and the modifications thereof is applied;

FIG. 35 is still another example of the electronic apparatus to whichthe display device with a touch detection function according to one ofthe embodiments and the modifications thereof is applied;

FIG. 36 is still another example of the electronic apparatus to whichthe display device with a touch detection function according to one ofthe embodiments and the modifications thereof is applied;

FIG. 37 is still another example of the electronic apparatus to whichthe display device with a touch detection function according to one ofthe embodiments and the modifications thereof is applied;

FIG. 38 is still another example of the electronic apparatus to whichthe display device with a touch detection function according to one ofthe embodiments and the modifications thereof is applied;

FIG. 39 is still another example of the electronic apparatus to whichthe display device with a touch detection function according to one ofthe embodiments and the modifications thereof is applied;

FIG. 40 is still another example of the electronic apparatus to whichthe display device with a touch detection function according to one ofthe embodiments and the modifications thereof is applied;

FIG. 41 is still another example of the electronic apparatus to whichthe display device with a touch detection function according to one ofthe embodiments and the modifications thereof is applied; and

FIG. 42 is still another example of the electronic apparatus to whichthe display device with a touch detection function according to one ofthe embodiments and the modifications thereof is applied.

DETAILED DESCRIPTION

Embodiments of the present disclosure will be explained below in detailwith reference to the accompanying drawings. Explanations are made inthe following order.

1. Overall configuration example

2. Basic principle of capacitive touch detection

3. Coupling example between power supply circuit and display device

4. Embodiments

5. Application examples

6. Aspects of the present disclosure

1. OVERALL CONFIGURATION EXAMPLE

FIG. 1 is a block diagram of a configuration example of a display devicewith a touch detection function according to the present disclosure. Adisplay device 1 with a touch detection function includes a display unit10 with a touch detection function, a control unit 11, a gate driver 12,a source driver 13, a source selector 13S, a drive electrode driver 14,and a touch detection unit 40. The display device 1 with a touchdetection function is a displaying device in which the display unit 10with a touch detection function is incorporated with a touch detectionfunction therein. The display unit 10 with a touch detection function isa so-called “in-cell” device having a capacitive touch detection device30 integrally incorporated into a liquid-crystal display unit 20 thatuses liquid-crystal display elements as display elements. The displayunit 10 with a touch detection function can be a so-called “on-cell”device having the capacitive touch detection device 30 mounted on theliquid-crystal display unit 20 that uses liquid-crystal display elementsas display elements. In the case of the on-cell device, the touchdetection device 30 can be provided on the liquid-crystal display unit20, or the touch detection device 30 can be provided above theliquid-crystal display unit 20 with another layer interposedtherebetween, not on the liquid-crystal display unit 20.

The liquid-crystal display unit 20 performs display by sequentiallyscanning horizontal lines one by one according to a scanning signalVscan supplied from the gate driver 12 as explained below. The controlunit 11 is a circuit that supplies a control signal to the gate driver12, the source driver 13, the drive electrode driver 14, and the touchdetection unit 40 based on a video signal Vdisp supplied from outside tocontrol these units to operate synchronously with each other. A controldevice according to the present disclosure includes the control unit 11,the gate driver 12, the source driver 13, and the drive electrode driver14.

The gate driver 12 has a function to sequentially select one horizontalline as a target for display drive of the display unit 10 with a touchdetection function based on the control signal supplied from the controlunit 11.

The source driver 13 is a circuit for supplying a pixel signal Vpix toeach of pixels Pix (sub-pixels SPix) of the display unit 10 with a touchdetection function based on the control signal supplied from the controlunit 11. The source driver 13 is supplied with, for example, R (red), G(green), and B (Blue) video data of 6 bits. The source driver 13generates a video signal Vsig in which a plurality of pixel signals Vpixcorresponding to respective sub-pixels SPix are time-divisionallymultiplexed, from the video data of one horizontal line and supplies thegenerated video signal Vsig to the source selector 13S. The sourcedriver 13 also generates a selection control signal Vsel required fordemultiplexing the pixel signals Vpix multiplexed into the video signalVsig and supplies the selection control signal Vsel to the sourceselector 13S together with the video signal Vsig. The source selector13S can reduce the number of wirings between the source driver 13 andthe liquid-crystal display unit 20.

The drive electrode driver 14 is a circuit that supplies atouch-detection drive signal (a touch drive signal, hereinafter alsosimply referred to as “drive signal”) VcomAC and a display drive voltageVcomDC as a display voltage to a drive electrode COML (explained later)of the display unit 10 with a touch detection function based on thecontrol signal supplied from the control unit 11.

The touch detection unit 40 is a circuit that detects whether or notthere is a touch (a contact state explained later) to the touchdetection device 30 based on the control signal supplied from thecontrol unit 11 and a touch detection signal Vdet supplied from thetouch detection device 30 of the display unit 10 with a touch detectionfunction and, when there is a touch, obtains coordinates and the like ofthe touch in a touch detection area. The touch detection unit 40includes an amplifier 42, an analog/digital (A/D) converter 43, a signalprocessor 44, a coordinator extractor 45, and a detection timingcontroller 46.

The amplifier 42 amplifies the touch detection signal Vdet supplied fromthe touch detection device 30. The amplifier 42 can include a low-passanalog filter that removes a high-frequency component (a noisecomponent) included in the touch detection signal Vdet, retrieves atouch component, and outputs these components.

In the following explanations, among constituent elements of the displaydevice 1 with a touch detection function illustrated in FIG. 1, thoseused primarily for display are also collectively referred to as “displaysection”. The “display section” includes, for example, theliquid-crystal display unit 20, the gate driver 12, the source driver13, and the drive electrode driver 14.

2. BASIC PRINCIPLE OF CAPACITIVE TOUCH DETECTION

The touch detection device 30 operates based on a basic principle ofcapacitive touch detection and outputs the touch detection signal Vdet.The basic principle of touch detection in the display device 1 with atouch detection function is explained with reference to FIGS. 1 to 6.FIG. 2 is an explanatory diagram illustrating a state where a finger isneither in contact with nor in proximity to the touch detection device30 for explaining the basic principle of the capacitive touch detection.FIG. 3 is an explanatory diagram of an example of an equivalent circuitof a state where a finger is neither in contact with nor in proximity tothe touch detection device 30 illustrated in FIG. 2. FIG. 4 is anexplanatory diagram illustrating a state where a finger is in contactwith or in proximity to the touch detection device 30 for explaining thebasic principle of capacitive touch detection. FIG. 5 is an explanatorydiagram of an example of an equivalent circuit of the state where afinger is in contact with or in proximity to the touch detection device30 illustrated in FIG. 4. FIG. 6 is an example of waveforms of a drivesignal and a touch detection signal.

For example, as illustrated in FIG. 2, a capacitive element C1 includesa pair of electrodes, that is, a drive electrode E1, and a touchdetection electrode E2 placed to face each other across a dielectricmaterial D. As illustrated in FIG. 3, one of ends of the capacitiveelement C1 is coupled to an AC signal source (a drive signal source) Sand the other end P thereof is grounded via a resistor R and is coupledto a voltage detector (a touch detector) DET. The voltage detector DETis an integration circuit included in the amplifier 42 illustrated inFIG. 1, for example.

When an AC rectangular wave Sg of a predetermined frequency (aboutseveral kilohertz to hundreds of kilohertz, for example) is applied fromthe AC signal source S to the drive electrode E1 (one end of thecapacitive element C1), an output waveform (the touch detection signalVdet) appears via the voltage detector DET coupled to a side of thetouch detection electrode E2 (the other end of the capacitive elementC1). The AC rectangular wave Sg corresponds to the drive signal VcomAC.

In a state (a non-contact state) where a finger is not in contact with(or in proximity to) the touch detection device 30, a current I₀corresponding to a capacitance value of the capacitive element C1 flowswith charging to and discharging from the capacitive element C1 asillustrated in FIGS. 2 and 3. At that time, a potential waveform at theother end P of the capacitive element C1 is like, for example, awaveform V₀ illustrated in FIG. 6 and the voltage detector DETillustrated in FIG. 3 detects the waveform V₀.

On the other hand, in a state (a contact state) where a finger is incontact with (or in proximity to) the touch detection device 30, acapacitance formed by the finger acts like a capacitive element C2 addedto the capacitive element C1 as illustrated in FIG. 4. In the equivalentcircuit illustrated in FIG. 5, the capacitive element C2 is added inseries with the capacitive element C1. In this state, currents I₁ and I₂flow through the capacitive elements C1 and C2 with charging to anddischarging from the capacitive elements C1 and C2, respectively. Apotential waveform at the other end P of the capacitive element C1 islike, for example, a waveform V₁ illustrated in FIG. 6 and the voltagedetector DET detects the waveform V₁. At that time, the potential of theother end P is a divided voltage potential determined by values of thecurrents I₁ and I₂ flowing through the capacitive elements C1 and C2,respectively. Accordingly, the waveform V₁ has a smaller value than thewaveform V₀ in the non-contact state. The voltage detector DET comparesthe detected voltage with a predetermined threshold voltage Vth anddetermines the non-contact state when the detected voltage is equal toor higher than the threshold voltage Vth while determining the contactstate when the detected voltage is lower than the threshold voltage Vth.The touch detection is achieved in this way.

The touch detection device 30 illustrated in FIG. 1 performs the touchdetection by sequentially scanning detection blocks one by one accordingto a drive signal Vcom (the drive signal VcomAC) supplied from the driveelectrode driver 14.

The touch detection device 30 outputs the touch detection signal Vdetwith respect to each detection block from a plurality of touch detectionelectrodes TDL explained later via the voltage detector DET illustratedin FIG. 3 or 5, to supply the touch detection signal Vdet to the A/Dconverter 43 of the touch detection unit 40.

The A/D converter 43 is a circuit that samples each analog signal outputfrom the amplifier 42 to convert the analog signal into a digital signalin the timing synchronized with the drive signal VcomAC.

The signal processor 44 includes a digital filter that reduces afrequency component (a noise component) of frequencies other than thatat which the drive signal VcomAC is sampled, included in an outputsignal from the A/D converter 43. The signal processor 44 is a logiccircuit that detects whether or not there is a touch to the touchdetection device 30 based on the output signal from the A/D converter43. The signal processor 44 compares the digitalized voltage detectorDET with the predetermined threshold voltage Vth and determines anon-contact state of an external proximity object when the digitalizedvoltage detector DET is equal to or higher than the threshold voltageVth. On the other hand, when the signal processor 44 compares thedigitalized voltage detector DET with the predetermined thresholdvoltage Vth and the digitalized voltage detector DET is lower than thethreshold voltage Vth, the signal processor 44 determines a contactstate of an external proximity object. In this way, the touch detectionunit 40 can perform the touch detection.

The coordinate extractor 45 is a logic circuit that obtains touch panelcoordinates of a touch when the touch is detected by the signalprocessor 44. The detection timing controller 46 executes a control tocause the A/D converter 43, the signal processor 44, and the coordinateextractor 45 to operate synchronously with each other. The coordinateextractor 45 outputs the touch panel coordinates as a signal outputVout.

FIG. 7 is an example of a module on which a display unit with a touchdetection function is mounted. As illustrated in FIG. 7, the displaydevice 1 with a touch detection function includes a pixel substrate 2 (athin film transistor (TFT) substrate 21) and a flexible printed circuitboard T. On the pixel substrate 2 (the TFT substrate 21), a chip onglass (COG) 19 is mounted, and a display area Ad of the liquid-crystaldisplay unit 20 and frame areas Gd are formed. The COG 19 is a chip ofan IC driver mounted on the TFT substrate 21 and is a control devicehaving circuits required for a display operation, such as the controlunit 11 and the source driver 13 illustrated in FIG. 1, incorporatedtherein. In the present example, the source driver 13 and the sourceselector 13S are formed on the TFT substrate. The source driver 13 andthe source selector 13S can be incorporated in the COG 19.Drive-electrode scanning units 14A and 14B, which are parts of the driveelectrode driver 14, are formed on the TFT substrate 21. The gate driver12 is formed as gate drivers 12A and 12B on the TFT substrate 21. In thedisplay device 1 with a touch detection function, circuits such as thedrive-electrode scanning units 14A and 14B and the gate driver 12 can beincorporated in the COG 19.

As illustrated in FIG. 7, drive electrode blocks B of a drive electrodeCOML and the touch detection electrodes TDL are formed tothree-dimensionally intersect in a direction perpendicular to the frontsurface of the TFT substrate 21.

The drive electrode COML is divided into a plurality of stripe electrodepatterns extending in one direction. When the touch detection operationis performed, the drive signal VcomAC is sequentially supplied to eachof the electrode patterns by the drive electrode driver 14. Each of thedrive electrode blocks B illustrated in FIG. 7 is stripe electrodepatterns of the drive electrode COML to which the drive signal VcomAC issupplied at the same time. The drive electrode blocks B (the driveelectrode COML) are arranged in a direction of the long side of thedisplay unit 10 with a touch detection function and the touch detectionelectrodes TDL are arranged in a direction of the short side of thedisplay unit 10 with a touch detection function. Outputs of the touchdetection electrodes TDL are provided on the short side of the displayunit 10 with a touch detection function and are coupled to the touchdetection unit 40 mounted on the flexible printed circuit board T viathe flexible printed circuit board T. As described above, the touchdetection unit 40 is mounted on the flexible printed circuit board T andis coupled to each of the touch detection electrodes TDL arranged inparallel. The flexible printed circuit board T is not essential and itsuffices to provide a terminal. In this case, the touch detection unit40 is provided outside of the module.

A drive signal generator explained later is incorporated in the COG 19.The source selector 13S is formed of TFT elements near the display areaAd on the TFT substrate 21. Many pixels Pix are arrayed in a matrix inthe display area Ad. The frame areas Gd and Gd are areas in which thepixels Pix are not arranged when the front surface of the TFT substrate21 is viewed in a perpendicular direction thereto. The gate driver 12and the drive-electrode scanning units 14A and 14B of the driveelectrode driver 14 are arranged on the frame areas Gd and Gd.

The gate driver 12 includes the gate drivers 12A and 12B and is formedof TFT elements on the TFT substrate 21. The gate drivers 12A and 12Bcan drive sub-pixels SPix (pixels) arrayed in a matrix in the displayarea Ad from both sides of the display area Ad, respectively. In thefollowing explanations, the gate driver 12A is also referred to as afirst gate driver 12A and the gate driver 12B is also referred to as asecond gate driver 12B. Scanning lines (not illustrated) are arrangedbetween the first gate driver 12A and the second gate driver 12B.Accordingly, the scanning lines are provided to extend in a directionparallel to an extension direction of the drive electrode COML in aperpendicular direction to the front surface of the TFT substrate 21.

The drive-electrode scanning units 14A and 14B are formed of TFTelements on the TFT substrate 21. The drive-electrode scanning units 14Aand 14B receive supply of the display drive voltage VcomDC via a displaywiring LDC and supply of the drive signal VcomAC via a touch wiring LACfrom the drive signal generator. The drive-electrode scanning units 14Aand 14B can drive each of the drive electrode blocks B arranged inparallel from both sides thereof, respectively. The display wiring LDCthat supplies the display drive voltage VcomDC and the touch wiring LACthat supplies the drive signal VcomAC are arranged in parallel in eachof the frame areas Gd and Gd. The display wiring LDC is arranged on aside nearer to the display area Ad than the touch wiring LAC. Thisstructure enables the display drive voltage VcomDC supplied by thedisplay wiring LDC to stabilize potential states of ends of the displayarea Ad. Accordingly, display is stabilized particularly in aliquid-crystal displaying device using liquid crystals according to alateral electric field mode.

The display device 1 with a touch detection function illustrated in FIG.7 outputs the touch detection signal Vdet from the short side of thedisplay unit 10 with a touch detection function. Accordingly, in thedisplay unit 10 with a touch detection function, wirings can be easilylaid during coupling to the touch detection unit 40 via the flexibleprinted circuit board T as a terminal unit.

The drive electrode COML functions as a drive electrode for theliquid-crystal display unit 20 and functions also as a drive electrodefor the touch detection device 30.

FIG. 8 is a perspective view of a configuration example of driveelectrodes and touch detection electrodes of a display unit with a touchdetection function. The drive electrode COML illustrated in FIG. 8 facesa pixel electrode in a perpendicular direction to the front surface ofthe TFT substrate 21. The touch detection device 30 includes the driveelectrode COML provided on the pixel substrate 2 and the touch detectionelectrodes TDL provided on a counter substrate 3. The touch detectionelectrodes TDL include stripe electrode patterns extending in adirection intersecting with the extension direction of the electrodepatterns of the drive electrode COML. The touch detection electrodes TDLface the drive electrode COML in the perpendicular direction to thefront surface of the TFT substrate 21. The electrode patterns of thetouch detection electrodes TDL are coupled to inputs of the amplifier 42of the touch detection unit 40, respectively. The electrode patterns ofthe drive electrode COML and the touch detection electrodes TDLintersecting with each other produce capacitances at intersectionsthereof, respectively. In the touch detection device 30, the driveelectrode driver 14 applies the drive signal VcomAC to the driveelectrode COML, so that the touch detection signal Vdet is output fromthe touch detection electrodes TDL, thereby performing the touchdetection. That is, the drive electrode COML corresponds to the driveelectrode E1 in the basic principle of the touch detection illustratedin FIGS. 2 to 6, the touch detection electrodes TDL correspond to thetouch detection electrode E2, and the touch detection device 30 detectsa touch according to the basic principle.

The touch detection electrodes TDL and the drive electrode COML (thedrive electrode blocks) are not limited to that of a form divided intoplural stripes. For example, the touch detection electrodes TDL or thedrive electrode COML (the drive electrode blocks) can be that of a combtine form. It suffices that the touch detection electrodes TDL and thedrive electrode COML (the drive electrode blocks) are divided intoplural pieces and shapes of slits dividing the drive electrode COML canbe linear or curved.

As illustrated in FIG. 8, the electrode patterns intersecting with eachother form a capacitive touch sensor in a matrix. Therefore, a positionwhere a contact or proximity of an external proximity object occurs canbe detected by scanning the entire touch detection surface of the touchdetection device 30. That is, in the touch detection device 30, when thetouch detection operation is performed, the drive electrode driver 14 isdriven to perform line-sequential scanning of the drive electrode blocksB illustrated in FIG. 7 in a time divisional manner. In this way, eachof the drive electrode blocks B (one detection block) of the driveelectrode COML is sequentially selected in a scanning direction Scan.The touch detection device 30 then outputs the touch detection signalVdet from each touch detection electrodes TDL. The touch detectiondevice 30 thus performs the touch detection of one detection block.

3. COUPLING EXAMPLE BETWEEN POWER SUPPLY CIRCUIT AND DISPLAY DEVICE

FIG. 9 is an example of coupling of a power supply IC (IntegratedCircuit) 100 to constituent elements of the display device 1 with atouch detection function. As illustrated in FIG. 9, the display device 1with a touch detection function includes the display unit 10 with atouch detection function, the gate driver 12, the source selector 13S,the drive electrode driver 14 (the drive-electrode scanning units 14Aand 14B), a test switching-element unit 15, the power supply IC 100, andsmoothing capacitors C11, C12, C13, and C14. The test switching-elementunit 15 includes a test switching element (not illustrated). The testswitching element operates, that is, is turned ON/OFF to apply a testsignal for checking an operation of the display section, for example,the display unit 10 with a touch detection function, to the displaysection. The test switching-element unit 15 is provided, for example,below the mounting position of the COG 19 illustrated in FIG. 7 but isnot limited thereto.

A power supply circuit 110 is provided inside of the power supply IC100. Wirings 101, 102, 103, and 104 are coupled to the power supplycircuit 110. The power supply circuit 110 outputs power supply voltagesVGH, VGL, TPH, and TPL to the wirings 101, 102, 103, and 104,respectively. The power supply circuit 110 supplies the power supplyvoltages VGH and VGL to the gate driver 12 to supply power to thedisplay unit 10 with a touch detection function. The power supplycircuit 110 supplies the power supply voltages TPH and TPL to the driveelectrode driver 14 to supply power to the display unit 10 with a touchdetection function.

A driver 111 is provided inside of the power supply IC 100. The driver111 is coupled between the wirings 101 and 102. The driver 111 operatesusing the power supply voltage VGH output to the wiring 101 and thepower supply voltage VGL output to the wiring 102 as a power supply. Awiring 105 is coupled to the driver 111. The driver 111 supplies acontrol signal to the source selector 13S via the wiring 105. Therefore,the power supply circuit 110 supplies the power supply voltage to thesource selector 13S to supply power to the display unit 10 with a touchdetection function.

The smoothing capacitors C11, C12, C13, and C14 are coupled to thewirings 101, 102, 103, and 104, respectively, on an output side of thepower supply circuit 110. The smoothing capacitors C11, C12, C13, andC14 are provided to correspond to the wirings of the power supplycircuit 110 and are inserted between the corresponding wirings and aground level, respectively.

When the voltages supplied by the corresponding power supply wiringsvary, the smoothing capacitors C11, C12, C13, and C14 perform charge anddischarge operations, respectively. That is, the smoothing capacitorsC11, C12, C13, and C14 are charged when the corresponding power supplyvoltages increase and are discharged when the corresponding power supplyvoltages decrease, respectively. Therefore, the smoothing capacitorsC11, C12, C13, and C14 can suppress variations in the voltages of thecorresponding wirings, respectively. The smoothing capacitors C11, C12,C13, and C14 can be provided on the TFT substrate 21 or the flexibleprinted circuit board T.

The display unit 10 with a touch detection function is a so-called“in-cell” device having the touch detection device 30 integrallyincorporated in the liquid-crystal display unit 20, and a displayoperation period and a touch detection period are not executed at thesame time but are present exclusively to avoid a noise influence.

The display operation period is a period in which display is performedon the liquid-crystal display unit 20 by sequentially scanninghorizontal lines one by one according to the scanning signal Vscansupplied from the gate driver 12.

The touch detection period is a period in which the touch detectionoperation of supplying the drive signal Vcom for the touch detectionfrom the drive electrode driver 14 to the drive electrode COML of thetouch detection device 30 based on the control signal supplied from thecontrol unit 11 to detect whether or not an external proximity object isin contact with or in proximity to the touch detection device 30 isperformed.

The display operation period and the touch detection period arealternately and repeatedly executed. A repetition cycle of the displayoperation period is, for example, 60 hertz and the touch detectionperiod has, for example, a repetition cycle several times higher thanthat of the display operation period. Therefore, depending on therepetition cycles of the display operation period and the touchdetection period, the voltages applied to the smoothing capacitors C11,C12, C13, and C14 inserted between the wirings 101, 102, 103, and 104 ofthe power supply IC 100 and the ground level, respectively, periodicallychange and the smoothing capacitors C11, C12, C13, and C14 vibrate,which may be recognized by a user as the audible noise. The same holdsfor the case where the display unit 10 with a touch detection functionis a so-called “on-cell” device. The on-cell device is a device havingthe touch detection device mounted on the liquid-crystal display unit.

4. EMBODIMENT

The display device 1 with a touch detection function according to thepresent disclosure has a power consumption unit that consumes powerduring the touch detection period. Consumption of power by the powerconsumption unit during the touch detection period enables to reducechanges in the voltages applied to the smoothing capacitors C11, C12,C13, and C14 inserted between the wirings 101, 102, 103, and 104 of thepower supply IC 100 and the ground level and to suppress or reduce theaudible noise of the smoothing capacitors, respectively. In thefollowing explanations, a potential higher than a predeterminedthreshold is also referred to as “H potential” and a potential lowerthan the predetermined threshold is also referred to as “L potential.”

First Embodiment

FIG. 10 is a configuration example of a power consumption unit accordingto a first embodiment. In the first embodiment, the source selector 13Scorresponds to the power consumption unit. In the first embodiment, thedisplay section does not include the source selector 13S.

In FIG. 10, the source selector 13S includes switches SWR, SWG, and SWBprovided to correspond to an R signal SigR, a G signal SigG, and a Bsignal SigB multiplexed into the video signal Vsig, respectively. Eachof the switches SWR, SWG, and SWB is constituted by an Nch MOStransistor (hereinafter, also referred to as NMOSTr) and a Pch MOStransistor (hereinafter, also referred to as PMOSTr) having sourcescoupled to each other and drains coupled to each other.

Selection signals SELR, SELG, SELB, xSELR, xSELG, and xSELB are input tothe source selector 13S. These selection signals SELR, SELG, SELB,xSELR, xSELG, and xSELB are included in the selection control signalVsel. The selection signal xSELR is a signal obtained by inverting theselection signal SELR. For example, the selection signal SELR can beinput to an inverter circuit and then the selection signal xSELR can beobtained as an output of the inverter circuit. The selection signalxSELG is a signal obtained by inverting the selection signal SELG. Forexample, the selection signal SELG can be input to an inverter circuitand then the selection signal xSELG can be obtained as an output of theinverter circuit. The selection signal xSELB is a signal obtained byinverting the selection signal SELB. For example, the selection signalSELB can be input to an inverter circuit and then the selection signalxSELB can be obtained as an output of the inverter circuit.

The selection signals SELR and xSELR are signals for selecting the Rsignal SigR. The selection signal SELR is input to a gate of the NMOSTrof the switch SWR. The selection signal xSELR is input to a gate of thePMOSTr of the switch SWR.

The selection signals SELG and xSELG are signals for selecting the Gsignal SigG. The selection signal SELG is input to a gate of the NMOSTrof the switch SWG. The selection signal xSELG is input to a gate of thePMOSTr of the switch SWG.

The selection signals SELB and xSELB are signals for selecting the Bsignal SigB. The selection signal SELB is input to a gate of the NMOSTrof the switch SWB. The selection signal xSELB is input to a gate of thePMOSTr of the switch SWB. A plurality of source selectors 13S can beprovided for one display section.

The source selector 13S turns ON/OFF the switches SWR, SWG, and SWB tooutput the R signal SigR, the G signal SigG, and the B signal SigB,respectively, in the display operation period. Therefore, normally, thesource selector 13S is not operated in the touch detection period, whichis a period other than the display operation period.

In the first embodiment, the source selector 13S is operated also in thetouch detection period to turn ON/OFF the switches SWR, SWG, and SWB andconsume power. Specifically, power is consumed by charging anddischarging parasitic capacitance components between the gate and sourceand between the gate and drain of each of the NMOSTr and the PMOSTrconstituting the respective switches SWR, SWG, and SWB. When theparasitic capacitance component is C, the voltage applied to the gatesof the NMOSTr and the PMOSTr is Vg, and the switching cycle between ONand OFF is f, the current i produced upon charging and discharging theparasitic capacitance component can be represented by an expression (1).i=C·Vg·f  (1)

The amount of consumed power is proportional to the magnitude of thecurrent i. Therefore, for example, the amount of power consumed byturning ON/OFF the switches SWR, SWG, and SWB can be adjusted byadjusting the switching cycle between ON and OFF. When the amount ofpower consumed by turning ON/OFF the switches SWR, SWG, and SWB isadjusted and the voltages applied to the smoothing capacitors C11 andC12 during the touch detection period are set substantially equal tothose applied to the smoothing capacitors C11 and C12 during the displayoperation period, the audible noise of the smoothing capacitors C11 andC12 can be suppressed or reduced.

Specifically, the switching cycles between ON and OFF of the switchesSWR, SWG, and SWB are adjusted such that power consumed by the units towhich the wirings 101 and 102 supply power is substantially the samebetween the touch detection period and the display operation period. Asa difference in the consumed power between the touch detection periodand the display operation period is smaller, periodic changes in thevoltages applied to the smoothing capacitors can be reduced more and theaudible noise of the smoothing capacitors can be suppressed or reducedmore. When the difference in the consumed power between the touchdetection period and the display operation period is, for example, lessthan 30%, the periodic changes in the voltages applied to the smoothingcapacitors can be reduced to such an extent that the audible noise ofthe smoothing capacitors can be suppressed or reduced.

First Operation Example of First Embodiment

FIG. 11 is a waveform chart representing a first operation example ofthe configuration illustrated in FIG. 10. In FIG. 11, a signal TSHD is asignal having an H potential in the touch detection period. In theperiod in which the signal TSHD has the H potential, that is, in thetouch detection period, the NMOSTrs of the switches SWR, SWG, and SWBare turned ON during periods in which the selection signals SELR, SELG,and SELB have H potentials, respectively, while the NMOSTrs of theswitches SWR, SWG, and SWB are turned OFF during periods in which theselection signals SELR, SELG, and SELB have L potentials, respectively.The PMOSTrs of the switches SWR, SWG, and SWB are turned ON duringperiods in which the selection signals xSELR, xSELG, and xSELB have Lpotentials, respectively, while the PMOSTrs of the switches SWR, SWG,and SWB are turned OFF during periods in which the selection signalsxSELR, xSELG, and xSELB have H potentials, respectively. The consumedpower in the touch detection period can be increased by controllingON/OFF of the switches SWR, SWG, and SWB in this way.

With reference to FIG. 11, it is indicated that the selection signalsxSELR, xSELG, and xSELB have the L potentials and the PMOSTrs of theswitches SWR, SWG, and SWB are ON during the periods in which theselection signals SELR, SELG, and SELB have the L potentials and theNMOSTrs of the switches SWR, SWG, and SWB are OFF. On the other hand,the selection signals SELR, SELG, and SELB have the H potentials and theNMOSTrs of the switches SWR, SWG, and SWB are ON during the periods inwhich the selection signals xSELR, xSELG, and xSELB have the Hpotentials and the PMOSTrs of the switches SWR, SWG, and SWB are OFF.

Accordingly, in the touch detection period, a state where at leasteither the NMOSTrs or the PMOSTrs are ON is maintained. That is, theNMOSTrs and the PMOSTrs are controlled to be ON/OFF in predeterminedcycles, respectively, to bring at least either the NMOSTrs or thePMOSTrs into the ON state in any timing of the touch detection period.Because at least either the NMOSTrs or the PMOSTrs are brought into theON state in any timing of the touch detection period, the R signal SigR,the G signal SigG, and the B signal SigB are fixed and a state where thevideo signal Vsig is coupled to the ground (grounded) is maintained,thereby preventing floating states of the R signal SigR, the G signalSigG, and the B signal SigB.

As described above, in the first embodiment, the source selector 13Sthat is normally provided to perform the selection operation during thedisplay operation period is operated to function as the powerconsumption unit also in the period other than the display operationperiod. In this way, the consumed power in the touch detection periodcan be set to be equal or close to the consumed power in the displayoperation period, so that the periodic changes in the voltages appliedto the smoothing capacitors can be reduced and the audible noise of thesmoothing capacitors can be suppressed or reduced.

In the first embodiment, the source selector 13S to be used for displaycontrol is caused to function as the power consumption unit, andtherefore it is not necessary to add a new member to suppress or reducethe audible noise of the smoothing capacitors. Furthermore, because thepower consumption of the source selector 13S can be adjusted by changingthe cycle at which the switches SWR, SWG, and SWB of the source selector13S are switched, the first embodiment can be easily applied to variousdisplay devices.

Second Operation Example of First Embodiment

When the transistors that constitute each of the switches SWR, SWG, andSWB of the source selector 13S are operated to be ON/OFF, noise into thedisplay section can be suppressed or reduced by setting the selectionsignals to match the timing when one transistor transitions from ON toOFF with the timing when another transistor transitions from OFF to ON,respectively.

For example, in the touch detection period, by setting the selectionsignals as illustrated in FIG. 12, the timings of transitions from OFFto ON are matched with the timings of transitions from ON to OFF withrespect to transistors constituting the switches SWR, SWG, and SWB. Forexample, timings of a change of the selection signal SELB from the Lpotential to the H potential match with timings of a change of theselection signal SELR from the H potential to the L potential,respectively, and timings of a transition of the NMOSTr of the switchSWB from OFF to ON match with timings of a transition of the NMOSTr ofthe switch SWR from ON to OFF, respectively. Timings of a change of theselection signal xSELG from the L potential to the H potential matchwith timings of a change of the selection signal xSELR from the Hpotential to the L potential, respectively, and timings of a transitionof the PMOSTr of the switch SWG from ON to OFF match with timings of atransition of the PMOSTr of the switch SWR from OFF to ON, respectively.

One of the source and drain of each of all the NMOSTrs and the PMOSTrsincluded in the switches SWR, SWG, and SWB is coupled to a signal linecoupled to the display section and the other of the source and drain ofeach of the NMOSTrs and the PMOSTrs is coupled to a signal line providedin common for all the NMOSTrs and the PMOSTrs. Furthermore, the controlis executed to match the timing of a transition of any one of transistorelements of the NMOSTrs and the PMOSTrs included in the switches SWR,SWG, and SWB from OFF to ON with the timing of a transition of anotherone of the transistor elements of the NMOSTrs and the PMOSTrs includedin the switches SWR, SWG, and SWB from ON to OFF, respectively.

In this way, noise in the display section can be suppressed or reducedby setting the selection signals to match the timing of a transition ofone of the transistors constituting the switches SWR, SWG, and SWB inthe source selector 13S from ON to OFF with the timing of a transitionof another one of the transistors from OFF to ON.

As explained with reference to FIG. 10, the video signal Vsig is inputto the source selector 13S via the signal line provided in common forthe switches SWR, SWG, and SWB. Accordingly, when a transistortransitions from OFF to ON or from ON to OFF in an arbitrary timing, theparasitic capacitance components between the gate and source and betweenthe gate and drain of the PMOSTr or the NMOSTr are charged anddischarged. When the parasitic capacitance components are charged anddischarged, a current flows and a variation in the voltage occurs in thesignal line provided in common to input the video signal Vsig to thedisplay section. The variation in the voltage may appear as noise in thedisplay section. Therefore, the source driver 13 that generates theselection control signal Vsel sets the selection signals to match thetiming of a transition of one transistor from OFF to ON with the timingof a transition of another transistor from ON to OFF, as in the secondoperation example, thereby canceling the change in the voltage. When thetransition timings are matched in this way, noise can be suppressed orreduced more than in a case where the transition timings are notmatched.

To achieve waveforms illustrated in FIG. 12, it suffices, for example,to prepare a selection signal as a base and to create a selection signaldelayed from the base selection signal by a third of the cycle and aselection signal delayed from the base selection signal by two thirds ofthe cycle. When phase differences of the three selection signals are setto thirds of the cycle, respectively, the three selection signals SELR,SELG, and SELB having phases equally shifted by thirds of the cycle,respectively, can be obtained.

While the phases are shifted by thirds of the cycle, respectively,because three colors of RGB are used in the second operation example, itsuffices to create a selection signal delayed from the base selectionsignal by a fourth of the cycle, a selection signal delayed by twofourths of the cycle, and a selection signal delayed by three fourths ofthe cycle when four colors of RGBW including white in addition to RGBare used. By setting phase differences of the four selection signals tofourths of the cycle, respectively, four selection signals having phasesequally shifted by fourths of the cycles, respectively, can be obtained.

When the transistors constituting the switches SWR, SWG, and SWB of thesource selector 13S are operated as in the second operation example,power consumption in the touch detection period can be set to be equalto or close to that in the display operation period while noise in thedisplay section is suppressed or reduced. Accordingly, periodic changesof the voltages applied to the smoothing capacitors can be reduced andthe audible noise of the smoothing capacitors can be suppressed orreduced.

Third Operation Example of First Embodiment

Alternatively, it is possible to operate some of the switches SWR, SWG,and SWB of the source selector 13S to be tuned ON and OFF and the othersto keep ON states thereof when the source selector 13S is caused tofunction as the power consumption unit also in the period other than thedisplay operation period. When the switches are operated to be turned ONand OFF, power is consumed by charging and discharging the parasiticcapacitance components mentioned above. Accordingly, the amount of powerconsumption can be adjusted by adjusting a ratio between the number ofswitches to keep the ON states thereof and the number of switches to beturned ON and OFF.

FIG. 13 is a waveform chart representing a third operation example ofthe first embodiment. For example, as illustrated in FIG. 13, theselection signal SELR and the selection signal SELG have reverse phasesand timings of a change of one of the selection signals from the Lpotential to the H potential match with timings of a change of the otherselection signal from the H potential to the L potential, respectively,in the touch detection period. Accordingly, in the touch detectionperiod, timings of a transition of the NMOSTr of the switch SWR from OFFto ON match with timings of a transition of the NMOSTr of the switch SWGfrom ON to OFF, respectively, and timings of a transition of the NMOSTrof the switch SWG from OFF to ON match timings of a transition of theNMOSTr of the switch SWR from ON to OFF, respectively.

Meanwhile, the selection signals xSELR, xSELG, and xSELB have the Lpotentials, respectively, the selection signal SELB has the H potential,and the PMOSTrs of the switches SWR, SWG, and SWB and the NMOSTr of theswitch SWB are kept in the ON states, respectively.

In this way, when some of the switches constituting the source selector13S are operated to be turned ON and OFF and the other switches are keptin the ON states, the amount of consumed power can be adjusted. In thethird operation example, the amount of consumed power is one third ofthat in the second operation example. The amount of consumed power canbe finely adjusted by adjusting ON periods and OFF periods of theswitches that are operated to be turned ON and OFF.

When some of switches constituting the source selector 13S are operatedto be turned ON and OFF, the selection signals are set to match thetiming of a transition of one transistor from ON to OFF with the timingof a transition of another transistor from OFF to ON, and thereby thepower consumption in the touch detection period can be set to be equalto or close to that in the display operation period while noise issuppressed or reduced as in the second operation example. Accordingly,the periodic changes of the voltages applied to the smoothing capacitorscan be reduced and the audible noise of the smoothing capacitors can besuppressed or reduced.

Second Embodiment

FIG. 14 is a configuration example of a power consumption unit accordingto a second embodiment. In the second embodiment, a test switchingelement 15SW corresponds to the power consumption unit. In the secondembodiment, a buffer 16 that outputs a signal of a ground level is usedduring the touch detection period. The buffer 16 functions as a signalapplication unit that applies, for example, the signal of the groundlevel in the touch detection period to a wiring that transmits the videosignal Vsig to the source selector 13S. In FIG. 14, the signal of theground level output from the buffer 16 is applied in the touch detectionperiod to the wiring that transmits the video signal Vsig to the sourceselector 13S. Accordingly, a voltage of a pixel signal line provided inthe display section that is coupled to the output side of the sourceselector 13S is set to the ground level in the touch detection period.

The test switching element 15SW is operated to apply a test signal tothe display section when a test for checking the operation of thedisplay section is performed. Generally, the operation of the displaysection is checked before an end product is completed. Checking of theoperation of the display section is performed, for example, before theCOG 19 is formed on the pixel substrate 2 but is not limited thereto.When the operation of the display section is to be checked, the testswitching element 15SW is brought into an ON state and the test signalfrom an evaluation board is applied to the test switching element 15SW,so that the test signal is applied to the display section via the testswitching element 15SW and the source selector 13S. By applying the testsignal to the display section, the operation of the display section ischecked.

After the operation of the display section is checked, the testswitching element 15SW is normally kept in an OFF state. For example, asin FIG. 15, which illustrates a comparative example to the secondembodiment, the power supply voltage VGL is applied to a gate of anNMOSTr of the test switching element 15SW and a voltage obtained byinverting the power supply voltage VGL with an inverter 15B is appliedto a gate of a PMOSTr of the test switching element 15SW. Accordingly,the test switching element 15SW is kept in the OFF state and the testswitching element 15SW is never used for some purposes from then.

On the other hand, in the second embodiment, the test switching element15SW that is normally not used after checking of the operation of thedisplay section is finished is operated in the touch detection period toconsume power. That is, because the test switching element 15SW that isnormally not used is caused to function as the power consumption unit inthe second embodiment, it is not necessary to add a new element orcircuit to suppress or reduce the audible noise of the smoothingcapacitors.

Referring back to FIG. 14, the selection signals SELR, SELG, and SELBare all fixed to H potentials and the selection signals xSELR, xSELG,and xSELB are all fixed to L potentials, respectively, in the touchdetection period. Accordingly, the NMOSTrs and the PMOSTrs of theswitches SWR, SWG, and SWB constituting the source selector 13S are allin ON states, respectively, in the touch detection period. In the touchdetection period, the signal of the ground level is applied from thebuffer 16 to the wiring that transmits the video signal Vsig and thevoltage of the pixel signal line provided in the display section is setto the ground level.

The test switching element 15SW has the NMOSTr and the PMOSTr. An outputof a buffer 15D is applied directly to the NMOSTr and the output of thebuffer 15D inverted by the inverter 15B is applied to the PMOSTr. Atoggle signal TSWTGL that has an H potential and an L potentialrepeating in a predetermined cycle is input to the buffer 15D and thusthe test switching element 15SW repeats an ON/OFF operation according tothe output of the buffer 15D.

FIG. 16 is a waveform chart representing an example of an operation ofthe second embodiment. For example, in the touch detection period, thetest switching element 15SW is in an ON state when the toggle signalTSWTGL has the H potential and is in an OFF state when the toggle signalTSWTGL has the L potential, as illustrated in FIG. 16. The testswitching element 15 SW functions as the power consumption unit thatconsumes power.

In the example illustrated in FIG. 16, the toggle signal TSWTGL hasperiods of the H potential and periods of the L potential on aone-to-one basis. Regarding the toggle signal TSWTGL, as the number ofchanges from the H potential to the L potential and from the L potentialto the H potential increases, that is, the cycle of voltage changes isshorter, the amount of power consumed by the test switching element 15SWbecomes larger. In other words, the amount of power consumed by the testswitching element 15SW can be adjusted by adjusting the length of aperiod “a” of the H potential of the toggle signal TSWTGL and the lengthof a period “b” of the L potential thereof illustrated in FIG. 17 toadjust the cycle (that is, a frequency) of changes in the potential ofthe toggle signal TSWTGL.

In the touch detection period, the signal of the ground level is appliedfrom the buffer 16 to the wiring that transmits the video signal Vsig.Accordingly, even when the test switching element 15SW repeats theON/OFF operation, a voltage value of a signal line between the testswitching element 15SW and the display section can be kept constant andnoise occurring to the source selector 13S and the display section isvery small. A plurality of source selectors 13S, test switching elements15SW, and buffers 16 can be provided for one display section.

The signal applied from the buffer 16 to the wiring that transmits thevideo signal Vsig in the touch detection period is not limited to thesignal of the ground level. For example, a signal of any fixed potentialother than the ground level can be applied from the buffer 16 to thewiring that transmits the video signal Vsig. By setting a state of thewiring coupled to the input terminal of the test switching element 15SWto a state in which the fixed potential of the same level is appliedthereto, a floating state, or a state where high impedance is prevented,the voltage of a pixel signal line provided in the display section thatis coupled to the output side of the source selector 13S is set to thefixed potential other than the ground level in the touch detectionperiod. In any of these cases, the voltage value of the signal linebetween the test switching element 15SW and the display section can bekept constant. Therefore, noise occurring to the source selector 13S andthe display section is very small.

FIGS. 18 to 20 are diagrams illustrating modifications of the secondembodiment in a case where a fixed potential other than a ground levelis applied to a wiring that transmits the video signal Vsig in a touchdetection period.

FIG. 18 is a diagram illustrating a first modification of the secondembodiment. As illustrated in FIG. 18, a potential applied from a buffer16B to the wiring that transmits the video signal Vsig via the testswitching element 15SW is, for example, a fixed potential Vgray. Apotential applied from a buffer 16A to the wiring that transmits thevideo signal Vsig in the touch detection period is also the fixedpotential Vgray. In a state where the same potentials Vgray are appliedin this way, power is consumed without affecting the source selector 13Sand the display section even when the test switching element 15SWrepeats the ON/OFF operation according to the toggle signal TSWTGL, andthus the audible noise of the smoothing capacitors can be suppressed orreduced.

A plurality of source selectors 13S, test switching elements 15SW, andbuffers 16A can be provided for one display section. In this case, fixedpotentials applied from the respective buffers 16A to the wiring thattransmits the video signal Vsig can be different values. For example, apositive fixed potential +Vgray and a negative fixed potential −Vgraycan be applied, respectively.

FIG. 19 is a diagram illustrating a second modification of the secondembodiment. As illustrated in FIG. 19, a signal obtained by invertingthe signal TSHD is applied to a gate of an NMOSTr of a switching element18SW and a signal obtained by inverting the signal obtained by invertingthe signal TSHD with an inverter 18B is applied to a gate of a PMOSTr ofthe switching element 18SW. The switching element 18SW is kept in an OFFstate in the touch detection period in which the signal TSHD has the Hpotential, that is, in the period in which the test switching element15SW repeats the ON/OFF operation according to the toggle signal TSWTGL.This configuration brings a wiring between the test switching element15SW and the switching element 18SW into a floating state. In thisfloating state, the fixed potential Vgray is applied from the buffer 16Ato the wiring that transmits the video signal Vsig in the touchdetection period. Accordingly, even when the test switching element 15SWrepeats the ON/OFF operation according to the toggle signal TSWTGL, thevoltage value of the signal line between the test switching element 15SWand the display section can be kept constant. Therefore, power can beconsumed and the audible noise of the smoothing capacitors can besuppressed or reduced without affecting the source selector 13S and thedisplay section.

In a period in which the signal TSHD has the L potential, it isdesirable to keep the switching element 18SW in an ON state and to setthe wiring between the test switching element 15SW and the switchingelement 18SW to the ground level.

A plurality of source selectors 13S, test switching elements 15SW, andbuffers 16A can be provided for one display section. In such a case,fixed potentials applied from the respective buffers 16A to the wiringthat transmits the video signal Vsig can be different values,respectively. For example, a positive fixed potential +Vgray and anegative fixed potential −Vgray can be applied, respectively.

FIG. 20 is a diagram illustrating a first modification of the thirdembodiment. The wiring coupled to the input terminal of the testswitching element 15SW is possibly in a high resistance state. Asillustrated in FIG. 20, sources of the NMOSTr and the PMOSTrconstituting the test switching element 15SW are coupled to the groundlevel via a resistor R. With this coupling state, it is possible toprevent the wiring coupled to the input terminal of the test switchingelement 15SW from being in a high resistance state.

In this coupling state, the fixed potential Vgray is applied from thebuffer 16A to the wiring that transmits the video signal Vsig in thetouch detection period. In the state where the fixed potential Vgray isapplied, even when the test switching element 15SW repeats the ON/OFFoperation according to the toggle signal TSWTGL, the voltage value ofthe signal line between the test switching element 15SW and the displaysection can be kept constant. Accordingly, power can be consumed and theaudible noise of the smoothing capacitors can be suppressed or reducedwithout affecting the source selector 13S and the display section.

A plurality of source selectors 13S, test switching elements 15SW, andbuffers 16A can be provided for one display section. In this case, fixedpotentials applied from the respective buffers 16A to the wiring thattransmits the video signal Vsig can be different values. For example, apositive fixed potential +Vgray and a negative fixed potential −Vgraycan be applied, respectively.

A case where the operation of the display section is checked using thetest switching element 15SW is explained with reference to FIG. 21. FIG.21 is a configuration example in a case where an operation of a displaysection is checked. When the operation of the display section is to bechecked, the power supply voltage VGH is applied to the gate of theNMOSTr of the test switching element 15SW and a voltage obtained byinverting the power supply voltage VGH with the inverter 15B is appliedto the gate of the PMOSTr of the test switching element 15SW. Thisconfiguration sets the test switching element 15SW in the ON state. Whena test signal is output from an evaluation board 17 with the testswitching element 15SW being set in the ON state, the test signal isapplied to the display section via the test switching element 15SW andthe source selector 13S. This application of the test signal enableschecking of the operation of the display section.

When a plurality of source selectors 13S and plural test switchingelements 15SW are provided for one display section, the test signaloutput from the evaluation board 17 is applied to the display sectionvia each of the test switching elements 15SW and each of the sourceselectors 13S, thereby checking the operation of the display section.

Third Embodiment

FIG. 22 is a configuration example of a power consumption unit accordingto a third embodiment. In the third embodiment, a MOS transistor 201 isprovided between wirings of power supply voltages and functions as thepower consumption unit.

A source of the MOS transistor 201 is coupled to the wiring 101 and adrain thereof is coupled to the wiring 102. A signal VcomSEL is suppliedto a gate of the MOS transistor 201. The signal VcomSEL has the samepotential as the power supply voltage VGL in the display operationperiod and the same potential as the power supply voltage VGH in thetouch detection period as illustrated in FIG. 23. Therefore, the MOStransistor 201 is brought into an ON state and a current flowstherethrough in the touch detection period, which is the period otherthan the display operation period. Accordingly, the MOS transistor 201consumes power in the touch detection period.

The signal VcomSEL can be a signal that has a state of having the samepotential as the power supply voltage VGL and a state of having the samepotential as the power supply voltage VGH continuously repeating in thetouch detection period, as illustrated in FIG. 24.

In the third embodiment, the amount of consumed power is adjusted by theMOS transistor 201 as described above and the voltages applied to thesmoothing capacitors C11 and C12 in the touch detection period arecaused to be substantially equal to the voltages applied thereto in thedisplay operation period, so that the audible noise of the smoothingcapacitors C11 and C12 can be suppressed or reduced.

Specifically, the period in which the MOS transistor 201 is turned ON isadjusted such that power consumption in the respective units to whichthe wirings 101 and 102 supply power is substantially the same betweenthe touch detection period and the display operation period. As adifference in the power consumption between the touch detection periodand the display operation period is smaller, the periodic changes of thevoltages applied to the smoothing capacitors can be reduced more and theaudible noise of the smoothing capacitors can be suppressed or reducedmore. When the difference in the power consumption between the touchdetection period and the display operation period is, for example,smaller than 30%, the periodic changes of the voltages applied to thesmoothing capacitors can be reduced to such an extent that the audiblenoise of the smoothing capacitors can be suppressed or reduced.

Fourth Embodiment

FIG. 25 is a configuration example of a power consumption unit accordingto a fourth embodiment. In the fourth embodiment, a capacitor isprovided as the power consumption unit. As illustrated in FIG. 25, acapacitor C10 is provided between the power supply circuit 110 and aground potential GND. In the fourth embodiment, the capacitor C10 iscontrolled to perform a charge and discharge operation to consume power.

The power supply circuit 110 outputs a signal CAP to the capacitor C10.The signal CAP has the same potential as the power supply voltage VGL inthe display operation period as illustrated in FIG. 26. The signal CAPhas a state of having the same potential as the power supply voltage VGLand a state of having the same potential as the power supply voltage VGHrepeating in the touch detection period. Accordingly, the capacitor C10repeats the charge operation and the discharge operation in the touchdetection period. Therefore, the capacitor C10 consumes power in thetouch detection period. When the repetition frequency of the signal CAPin the touch detection period and the capacitance of the capacitor C10are appropriately set, the amount of consumed power of the displaydevice 1 with a touch detection function in the touch detection periodcan be adjusted. By adjusting the amount of consumed power due to thecharge operation and the discharge operation of the capacitor C10 andcausing the voltages applied to the smoothing capacitors C11 and C12 inthe touch detection period to be substantially equal to the voltagesapplied thereto in the display operation period, the audible noise ofthe smoothing capacitors C11 and C12 can be suppressed or reduced.

Specifically, the repetition frequency of the signal CAP in the touchdetection period and the capacitance of the capacitor C10 are adjustedto set power consumption in the respective units to which power issupplied by the wirings 101 and 102 to be substantially the same in thetouch detection period and the display operation period.

As a difference between the power consumption in the touch detectionperiod and the power consumption in the display operation period issmaller, the periodic changes of the voltages applied to the smoothingcapacitors can be reduced more and the audible noise of the smoothingcapacitors can be suppressed or reduced more. When the power consumptiondifference between the touch detection period and the display operationperiod is, for example, smaller than 30%, the periodic changes of thevoltages applied to the smoothing capacitors can be reduced to such anextent that the audible noise of the smoothing capacitors can besuppressed or reduced.

The capacitor C10 can be provided on the TFT substrate 21 or theflexible printed circuit board T.

Fifth Embodiment

In the embodiments described above, examples where power consumption ofthe display section as the constituent element for display is set to besubstantially equal between the touch detection period and the displayoperation period have been explained. However, the display device 1 witha touch detection function can be configured to set power consumptionincluding that of other constituent elements to be substantially equalbetween the touch detection period and the display operation period.

FIG. 27 is a configuration example of a case where power consumptionincluding that of constituent elements other than a display section isset to be substantially equal between a touch detection period and adisplay operation period. In the example illustrated in FIG. 27, dummyswitches provided in the drive-electrode scanning unit 14A are assumedas a power consumption unit.

As illustrated in FIG. 27, the drive-electrode scanning unit 14Aincludes shift registers SR1, SR2, and SR3, NAND gates N1, N2, and N3,and select switches SEL-SW1, SEL-SW2, and SEL-SW3. These are constituentelements generally provided in the display device with a touch detectionfunction. Whether or not there is a touch to the touch detection device30 is detected by inputting drive signals Vcom1, Vcom2, and Vcom3 outputfrom the drive-electrode scanning unit 14A to the touch detection device30.

In the embodiment, inverters INV1 and INV2 and dummy select switchesSWL-SWDM1 and SEL-SWDM2 are added to the configuration mentioned above.Output signals out1, out2, and out3 from the shift registers SR1, SR2,and SR3 are input to first input terminals of the NAND gates N1, N2, andN3, respectively. The signal VcomSEL is input to second input terminalsof the NAND gates N1, N2, and N3.

Each of the select switches SEL-SW1, SEL-SW2, and SEL-SW3 and the dummyselect switches SEL-SWDM1 and SEL-SWDM2 is constituted by an NMOSTr anda PMOSTr having drains coupled to each other. Output signals of the NANDgates N1, N2, and N3 are input to respective gates of the NMOSTrs andthe PMOSTrs constituting the select switches SEL-SW1, SEL-SW2, andSEL-SW3, respectively. The power supply voltage TPH is input to a sourceof each of the PMOSTrs constituting the select switches SEL-SW1,SEL-SW2, and SEL-SW3 and the power supply voltage TPL is input to asource of each of the NMOSTrs constituting the select switches SEL-SW1,SEL-SW2, and SEL-SW3.

The drive signals Vcom1, Vcom2, and Vcom3 are output from the drains ofthe NMOSTrs and PMOSTrs constituting the select switches SEL-SW1,SEL-SW2, and SEL-SW3, respectively. The drive signals Vcom1, Vcom2, andVcom3 are input to the display unit 10 with a touch detection function.

The signal VcomSEL is input to the inverters INV1 and INV2. Outputsignals of the inverters INV1 and INV2 are input to respective gates ofthe NMOSTrs and the PMOSTrs constituting the dummy select switchesSEL-SWDM1 and SEL-SWDM2, respectively.

The power supply voltage TPH is input to a source of each of the PMOSTrsconstituting the dummy select switches SEL-SWDM1 and SEL-SWDM2 and thepower supply voltage TPL is input to a source of each of the NMOSTrsconstituting the dummy select switches SEL-SWDM1 and SEL-SWDM2.

The drains of the NMOSTrs and the PMOSTrs constituting the dummy selectswitches SEL-SWDM1 and SEL-SWDM2 are coupled to no unit. Therefore,dummy outputs Vcom Dummy1 and Vcom Dummy 2 output from the dummy selectswitches SEL-SWDM1 and SEL-SWDM2, respectively, are used to consumepower.

An operation of the drive-electrode scanning unit 14A is explained nextwith reference to FIG. 28. In a period in which the signal out1 outputfrom the shift register SR1 has an H potential in FIG. 28, a signalVcomSELout1 obtained by inverting the signal VcomSEL is input by theNAND gate N1 to the gates of the NMOSTr and the PMOSTr constituting theselect switch SEL-SW1. Accordingly, the NMOSTr and the PMOSTrconstituting the select switch SEL-SW1 are alternately turned ON, sothat the power supply voltage TPH and the power supply voltage TPL arealternately input to the touch detection device 30 as the drive signalVcom1.

In a period in which the signal out2 output from the shift register SR2has an H potential, a signal VcomSELout2 obtained by inverting thesignal VcomSEL is input by the NAND gate N2 to the gates of the NMOSTrand the PMOSTr constituting the select switch SEL-SW2. Accordingly, theNMOSTr and the PMOSTr constituting the select switch SEL-SW2 arealternately turned ON, so that the power supply voltage TPH and thepower supply voltage TPL are alternately input as the drive signal Vcom2to the touch detection device 30.

In a period in which the signal out3 output from the shift register SR3has an H potential, a signal VcomSELout3 obtained by inverting thesignal VcomSEL is input by the NAND gate N3 to the gates of the NMOSTrand the PMOSTr constituting the select switch SEL-SW3. Accordingly, theNMOSTr and the PMOSTr constituting the select switch SEL-SW3 arealternately turned ON and thus the power supply voltage TPH and thepower supply voltage TPL are alternately input as the drive signal Vcom3to the touch detection device 30.

The signal VcomSEL is input to the inverters INV1 and INV2 and theoutput signals from the inverters INV1 and INV2 are input to the gatesof the NMOSTrs and the PMOSTrs constituting the dummy select switchesSEL-SWDM1 and SEL-SWDM2, respectively. Therefore, the NMOSTr and thePMOSTr constituting the dummy select switch SEL-SWDM1 are alternatelyturned ON and thus the power supply voltage TPH and the power supplyvoltage TPL alternately become the dummy output Vcom Dummy1. The NMOSTrand the PMOSTr constituting the dummy select switch SEL-SWDM2 are alsoalternately turned ON and thus the power supply voltage TPH and thepower supply voltage TPL alternately become the dummy output VcomDummy2.

Power is consumed by turning ON the dummy select switches SEL-SWDM1 andSEL-SWDM2 in this way.

In a case of DC-DC drive, the power supply voltages VGH and VGL areconsumed because the drive-electrode scanning unit 14A is turned ON andOFF in the touch detection period. However, power consumption in thetouch detection period is less than power consumption in the displayoperation period. For example, power consumption in the touch detectionperiod is about one third of that in the display operation period.Accordingly, in the first modification, the two dummy select switchesSEL-SWDM1 and SEL-SWDM2 are added and are turned ON and OFF in the touchdetection period. As a result, the amount of consumed power in the touchdetection period can be tripled and thus the amount of consumed powersubstantially identical to that in the display operation period can beachieved in the touch detection period.

In the embodiment, the power consumption of the display device 1 with atouch detection function in the touch detection period can be adjustedby increasing or decreasing the number of dummy select switches. Byadjusting the number of dummy select switches and setting the voltagesapplied to the smoothing capacitors C13 and C14 in the touch detectionperiod to be substantially equal to the voltages applied thereto in thedisplay operation period, the audible noise of the smoothing capacitorsC13 and C14 can be suppressed or reduced. Specifically, the number ofdummy select switches is adjusted to set power consumption in therespective units to which power is supplied by the wirings 103 and 104to be substantially equal between the touch detection period and thedisplay operation period. As a difference between the power consumptionin the touch detection period and the power consumption in the displayoperation period is smaller, the periodic changes of the voltagesapplied to the smoothing capacitors can be reduced more and the audiblenoise of the smoothing capacitors can be suppressed or reduced more.When the difference in the power consumption between the touch detectionperiod and the display operation period is, for example, less than 30%,the periodic changes of the voltages applied to the smoothing capacitorscan be reduced to such an extent that the audible noise of the smoothingcapacitors can be suppressed or reduced.

First Modification

The first to fifth embodiments can be independently carried out.Accordingly, several ones of the first to fifth embodiments can becombined. When the amount of power that can be consumed by carrying outone of the first to fifth embodiments is small, consumed power may beappropriately set by combining other one or more of the first to fifthembodiments.

Second Modification

Cases where a first period in which predetermined power is consumed isthe display operation period and a second period in which less power isconsumed than in the first period is the touch detection period havebeen explained above. However, the first and second periods are notlimited thereto. The first period and the second period can be a periodin which relatively more power is consumed among periods between whichpower consumption of at least one of the constituent elements of thedisplay device changes periodically and a period in which relativelyless power is consumed, respectively.

Comparative Example

A case where configurations of the embodiments described above are notadopted is explained.

In a case where the touch detection operation is performed once orplural times while the display device performs the display operation ofone screen, the display operation period and the touch detection periodmay be provided as operation states. The display operation period is aperiod in which predetermined power is consumed and the touch detectionperiod is a period in which less power is consumed than in the displayoperation period.

FIG. 29 is a waveform chart representing an example of changes in thepower supply voltages VGL and VGH and the voltage value of the drivesignal Vcom in a touch detection period and a display operation period.As illustrated in FIG. 29, the power supply voltages VGL and VGH and thevoltage value of the drive signal Vcom change according switchingbetween the display operation period and the touch detection period.Particularly, with respect to the power voltage VGL, power is consumedless in the touch detection period while power is consumed more in thedisplay operation period. That is, with respect to the display unit 10,there are the first period (the display operation period) in whichpredetermined power is consumed and the second period (the touchdetection period) in which less power is consumed than in the firstperiod.

As illustrated in FIG. 29, the display device repeats the displayoperation period and the touch detection period, so that powerconsumption changes periodically (at 3.2 kilohertz, for example). Whenthe power consumption changes periodically, the voltages applied to thesmoothing capacitors change periodically and thus the smoothingcapacitor vibrates. Therefore, when the cycle in which the powerconsumption changes is included in an audible range, vibrations of thesmoothing capacitors may be heard as the audible noise.

Accordingly, by consuming power that is normally not consumed in thetouch detection period as in the above embodiments, a difference betweenpower consumption in the display operation period and power consumptionin the touch detection period can be eliminated or reduced, vibrationsof the smoothing capacitors can be eliminated or reduced, and theaudible noise can be suppressed or reduced.

5. APPLICATION EXAMPLES

With reference to FIGS. 30 to 42, application examples of the displaydevice 1 with a touch detection function explained in the aboveembodiments and modifications are explained. FIGS. 30 to 42 illustrateexamples of an electronic apparatus to which the display device 1 with atouch detection function according to one of the embodiments and themodifications thereof is applied. It is possible to apply the displaydevice 1 with a touch detection function according to the aboveembodiments and modifications to electronic apparatuses in any field,including a television device, a digital camera, a laptop personalcomputer, a portable terminal device such as a portable phone, a videocamera, and the like. In other words, it is possible to apply thedisplay device 1 with a touch detection function according to the aboveembodiments and modifications to electronic apparatuses in any field,which display a video signal input externally or a video signalgenerated internally as an image or a video.

Application Example 1

An electronic apparatus illustrated in FIG. 30 is a television device towhich the display device 1 with a touch detection function according tothe above embodiments and modifications is applied. This televisiondevice includes a video display screen unit 510 that includes a frontpanel 511 and a filter glass 512, for example. The video display screenunit 510 is the display device 1 with a touch detection functionaccording to the above embodiments and modifications.

Application Example 2

An electronic apparatus illustrated in FIGS. 31 and 32 is a digitalcamera to which the display device 1 with a touch detection functionaccording to the above embodiments and modifications is applied. Thisdigital camera includes a flash-light producing unit 521, a display unit522, a menu switch 523, and a shutter button 524, for example. Thedisplay unit 522 is the display device 1 with a touch detection functionaccording to the above embodiments and modifications.

Application Example 3

An electronic apparatus illustrated in FIG. 33 is a video camera towhich the display device 1 with a touch detection function according tothe above embodiments and modifications is applied, and FIG. 33illustrates its external appearance. This video camera includes a mainunit 531, a subject capturing lens 532 that is provided on the frontside of the main unit 531, an image-capturing start/stop switch 533, anda display unit 534, for example. The display unit 534 is the displaydevice 1 with a touch detection function according to the aboveembodiments and modifications.

Application Example 4

An electronic apparatus illustrated in FIG. 34 is a laptop personalcomputer to which the display device 1 with a touch detection functionaccording to the above embodiments and modifications is applied. Thislaptop personal computer includes a main unit 541, a keyboard 542 for anoperation to input text and the like, and a display unit 543 thatdisplays an image. The display unit 543 is the display device 1 with atouch detection function according to the above embodiments andmodifications.

Application Example 5

An electronic apparatus illustrated in FIGS. 35 to 41 is a portablephone to which the display device 1 with a touch detection functionaccording to the above embodiments and modifications is applied. FIG. 35is a front view of a state where the portable phone is opened, FIG. 36is a right side view of a state where the portable phone is opened, FIG.37 is a front view of a state where the portable phone is folded, FIG.38 is a left side view of a state where the portable phone is folded,FIG. 39 is a right side view of a state where the portable phone isfolded, FIG. 40 is a plan view of a state where the portable phone isfolded, and FIG. 41 is a bottom view of a state where the portable phoneis folded. This portable phone is configured by coupling an upper casing551 and a lower casing 552 by a coupling unit (a hinge) 553, andincludes a display 554, a sub-display 555, a picture light 556, and acamera 557. The display 554 or the sub-display 555 is the display device1 with a touch detection function according to the above embodiments andmodifications.

Application Example 6

An electronic apparatus illustrated in FIG. 42 is a portable informationterminal that operates as a portable computer, a multi-functionalportable phone, a portable computer capable of making a voice call, or aportable computer capable of other forms of communication, and that isalso referred to as so-called “smartphone” or “tablet terminal”. Thisportable information terminal includes a display unit 562 on a surfaceof a casing 561, for example. The display unit 562 is the display device1 with a touch detection function according to the above embodiments andmodifications.

While the present disclosure has been explained above by describingembodiments and application examples thereof to an electronic device,the present disclosure is not limited to the above embodiments and thelike, and various modifications can be made.

For example, in the above embodiments and the like, the touch sensor hasbeen explained as a capacitance-type sensor; however, the presentdisclosure is not limited thereto, and instead of a capacitance-typesensor, for example, an optical sensor or a resistive sensor can beused.

Furthermore, for example, in the above embodiments and the like, thedisplay element has been explained as a liquid-crystal display element;however, the present disclosure is not limited thereto, and instead of aliquid-crystal display element, an EL (Electro Luminescence) element canbe used.

Further, in the above embodiments and the like, the first period is adisplay operation period of the display device 1 with a touch detectionfunction and the second period is a touch detection period of thedisplay device 1 with a touch detection function; however, these periodsare not limited thereto, and the present disclosure can be applied to adevice that has a first period to consume predetermined power and asecond period to consume less power than in the first period, andrepeats the first period and the second period to periodically changepower consumption.

6. ASPECTS OF THE PRESENT DISCLOSURE

The present disclosure includes aspects as follows.

(1) A display device comprising:

a display section that has a first period to consume predetermined powerand a second period to consume less power than in the first period, andpower consumption of which periodically changes by repeating the firstperiod and the second period;

a smoothing capacitor that stabilizes power supplied to the displaysection; and

a power consumption unit that consumes the supplied power in the secondperiod.

(2) The display device according to (1), wherein

the display section has a touch detection device incorporated in adisplaying device in an integrated manner,

the first period is a display operation period of the displaying device,and

the second period is a touch detection period of the touch detectiondevice.

(3) The display device according to (1), further comprising a testswitching element that operates to apply a test signal to the displaysection when a test for checking an operation of the display isperformed, wherein

the power consumption unit consumes power by causing the test switchingelement to operate in the second period.

(4) The display device according to (3), further comprising a signalapplication unit that applies a signal for keeping a voltage value of asignal line located between the test switching element and the displaysection constant to the signal line in the second period.

(5) The display device according to (4), wherein the signal for keepinga voltage value of the signal line constant is a signal for setting avoltage value of a pixel signal line provided in the display section toa predetermined voltage value in the second period.

(6) The display device according to (1), wherein

the power consumption unit includes a switching element that operates inthe first period, and

the switching element operates also in the second period to consume thesupplied power.

(7) The display device according to (6), wherein

the switching element includes a first transistor element and a secondtransistor element,

the first and second transistor elements are controlled to be turned ONand OFF in predetermined cycles, respectively, to bring at least one ofthe first and second transistor elements in an ON state in any timing inthe second period, and

the predetermined cycles are set according to power consumption of thedisplay section in the first period.

(8) The display device according to (7), wherein

the number of the switching element included in the power consumptionunit is plural,

sources of the first transistor element and the second transistorelement included in each switching element are coupled to each other anddrains thereof are coupled to each other,

one of the source and the drain of each of the first and secondtransistor elements included in a first switching element is coupled toa signal line coupled to the display section, and other of the sourceand the drain of each of the first and second transistor elements iscoupled to a signal line provided in common with the first and secondtransistor elements included in a second switching element, and

the power consumption unit is controlled to match timing of a transitionof any one of the first and second transistor elements included in thefirst switching element from OFF to ON with timing of a transition ofany one of the first and second transistor elements included in thesecond switching element from ON to OFF.

(9) The display device according to (8), wherein the power consumptionunit is controlled to set some of the first and second transistorelements of the switching elements included therein to be always in ONstates in the second period.

(10) The display device according to (8), wherein each switching elementis provided to correspond to one of plural kinds of color signalsincluded in a video signal corresponding to an image to be displayed onthe display section, respectively.

(11) The display device according to (1), wherein

the power consumption unit includes a dummy element that operateswithout affecting an operation of the display section in the firstperiod, and

the dummy element operates in the second period to consume the suppliedpower.

(12) The display device according to (1), further comprising a switchingelement that operates in the second period, wherein

the power consumption unit includes a dummy element that operates withthe switching element and operates without affecting an operation of thedisplay section, and

the dummy element operates in the second period to consume the suppliedpower.

(13) The display device according to (12), wherein the power consumptionunit includes a predetermined number of the dummy elements, thepredetermined number corresponding to power consumption of the displaysection in the first period and power consumption of the switchingelement in the second period.

(14) The display device according to (1), wherein

the power consumption unit includes a capacitor that performs a chargeand discharge operation using the supplied power, and

the capacitor performs the charge and discharge operation in the secondperiod.

(15) An electronic apparatus comprising the display device according to(1).

(16) The display device according to the (1), wherein

the display section includes a touch detection device mounted on adisplaying device,

the first period is a display operation period of the displaying device,and

the second period is a touch detection period of the touch detectiondevice.

According to the present disclosure, the power consumption unit consumessupplied power in the second period. Therefore, a display device and anelectronic apparatus that can suppress or reduce the audible noise of asmoothing capacitor can be achieved.

It should be understood that various changes and modifications to thepresently preferred embodiments described herein will be apparent tothose skilled in the art. Such changes and modifications can be madewithout departing from the spirit and scope of the present subjectmatter and without diminishing its intended advantages. It is thereforeintended that such changes and modifications be covered by the appendedclaims.

The invention is claimed as follows:
 1. A display device comprising: adisplay section that includes a display unit and a touch detectiondevice, the touch detection device incorporated in the display unit inan integrated manner, that has a display operation period to perform adisplay operation and a touch detection period to perform a touchdetection operation, and power consumption of which periodically changesby repeating the display operation period and the touch detection periodby a time-divisionally multiplexed method; a power supply circuit thatsupplies power to the display section via a driver for driving displayelements of the display section; a smoothing capacitor that stabilizespower supplied to the driver; and a power consumption unit that consumespower in the power supply circuit in the touch detection period, whereinthe driver is a source driver or a gate driver, the power consumptionunit includes a switching element that operates in the display operationperiod and that also operates in the touch detection period to consumepower supplied to the gate driver, the switching element includes afirst transistor element and a second transistor element, the first andsecond transistor elements are controlled to be turned ON and OFF inpredetermined cycles, respectively, to bring at least one of the firstand second transistor elements in an ON state in any timing in the touchdetection period, and the predetermined cycles are set according topower consumption of the display section in the display operationperiod.
 2. The display device according to claim 1, wherein the powerconsumption unit consumes power in the touch detection period such thatan amount of power supplied to the driver in the display operationperiod is equal to an amount of power supplied to the driver in thetouch detection period.
 3. The display device according to claim 1,further comprising a test switching element that operates to apply atest signal to the display section when a test for checking an operationof the display section is performed, wherein the power consumption unitconsumes power supplied to the gate driver by causing the test switchingelement to operate in the touch detection period.
 4. The display deviceaccording to claim 3, wherein the display operation period and the touchdetection period are not simultaneously executed and are mutuallyexclusive.
 5. The display device according to claim 3, furthercomprising a signal application unit that applies a signal for keeping avoltage of a signal line located between the test switching element andthe display section at a constant value to the signal line in the touchdetection period.
 6. The display device according to claim 5, whereinthe signal is a signal for setting a voltage value of a pixel signalline provided in the display section to a predetermined voltage value inthe touch detection period.
 7. The display device according to claim 1,wherein the power consumption unit includes a plurality of switchingelements, sources of the first transistor element and the secondtransistor element included in each switching element are coupled toeach other and drains thereof are coupled to each other, one of thesource and the drain of each of the first and second transistor elementsincluded in a first switching element is coupled to a signal linecoupled to the display section, and the other of the source and thedrain of each of the first and second transistor elements is coupled toa signal line provided in common with the first and second transistorelements included in a second switching element, and the powerconsumption unit is controlled to match timing of a transition of anyone of the first and second transistor elements included in the firstswitching element from OFF to ON with timing of a transition of any oneof the first and second transistor elements included in the secondswitching element from ON to OFF.
 8. The display device according toclaim 7, wherein the power consumption unit is controlled to set some ofthe first and second transistor elements of the switching elementsincluded therein to be always in ON states in the touch detectionperiod.
 9. The display device according to claim 7, wherein each of theswitching elements is provided to correspond to one of plural kinds ofcolor signals included in a video signal corresponding to an image to bedisplayed on the display section.
 10. The display device according toclaim 1, wherein the driver includes a drive electrode driver thatsupplies a display drive voltage to the display section in the displayoperation period and that supplies a touch detection drive signal to thedisplay section in the touch detection period, and the power consumptionunit includes a dummy element that operates without affecting anoperation of the display section in the display operation period andthat operates in the touch detection period to consume power supplied tothe drive electrode driver.
 11. The display device according to claim 1,further comprising a switching element that operates in the touchdetection period, wherein the driver includes a drive electrode driverthat applies a display drive voltage to the display section in thedisplay operation period and that supplies a touch detection drivesignal to the display section in the touch detection period, and thepower consumption unit includes a dummy element that operates togetherwith the switching element without affecting an operation of the displaysection, and that operates in the touch detection period to consumepower supplied to the drive electrode driver.
 12. The display deviceaccording to claim 11, wherein the power consumption unit includes apredetermined number of the dummy elements, the predetermined numbercorresponding to power supplied to the drive electrode driver in thedisplay operation period and power supplied to the drive electrodedriver in the touch detection period.
 13. The display device accordingto claim 1, wherein the driver includes a drive electrode driver thatapplies a display drive voltage to the display section in the displayoperation period and that supplies a touch detection drive signal to thedisplay section in the touch detection period, and the power consumptionunit includes a capacitor that performs a charge and discharge operationusing power supplied to the drive electrode driver and that performs thecharge and discharge operation in the touch detection period.
 14. Anelectronic apparatus comprising the display device according to claim 1.